Fuel injection apparatus

ABSTRACT

A fuel injection apparatus for delivering a metered quantity of fuel to an engine comprising a valve controlled port through which the metered quantity of fuel is delivered to the engine the valve being resiliently urged to a position to close said port. .Iadd.An .Iaddend..[.Electromagnetic means.]. .Iadd.electromagnetic element is provided which is .Iaddend.operable when energized to displace said valve member from the closed position to permit delivery of the metered quantity of fuel through the port to the engine. The electromagnetic .[.means including.]. .Iadd.element includes .Iaddend.an armature member movable in a first direction in response to energizing of the electromagnetic .[.means.]. .Iadd.element .Iaddend.to effect the opening of the port. The armature .[.having.]. .Iadd.has .Iaddend.a limited free movement in the first and the opposite directions independent of the valve member when the electromagnetic .[.means.]. .Iadd.means .Iaddend.is not energized and the valve member is in the port closed position.

This invention relates to apparatus for the injecting of an meteredquantities of fuel to an internal combustion engine, including suchapparatus where the fuel is entrained in air or other suitable gasduring injection.

In currently known fuel injecting apparatus, it is customary to use aselectively openable port to regulate, in relation to the engine cycle,the timing of admission of the fuel and/or the period over which thefuel is delivered to the engine. The port is normally controlled by avalve, usually of the pintle or poppet type, with the valve beingactuated by a solenoid which is energised under the control of anappropriate electronic circuit. Having regard to the normal speed ofoperation of modern internal combustion engines, particularly in theautomotive and outboard marine areas, the valve controlling theinjection of the fuel to an engine is required to operate at arelatively high frequency and with substantial accuracy in regard to thetiming of the opening and closing of the valve.

It is therefore the principal object of the present invention toprovide, in a fuel injection apparatus for delivering fuel to aninternal combustion engine, a valve controlled port and valve actuatingmechanism which is reliable in operation and can provide the requiredaccuracy and durability demanded by modern high speed engines.

With this object in view, there is provided a fuel injection apparatus,for delivering a metered quantity of fuel into the air induction systemor combustion chamber of an engine comprising a port through which themetered quantity of fuel is delivered, a valve member operable to openand close said port, means resiliently urging said valve member to aposition to close said port, and selectively energisable electromagneticmeans operable when energised to displace said valve member from a portclosed position to permit delivery of the metered quantity of fuelthrough the port, said electromagnetic means including an armaturemember movable in a first direction in response to energising of theelectromagnetic means to effect said displacement of the valve member toopen the port, said armature having limited free movement in said firstand the opposite directions independent of the valve member when theelectromagnetic means is not energised and the valve member is in theport closed position.

The limited freedom of movement of the armature member in the oppositedirection enables the armature member to continue movement in saidopposite direction after the valve member has returned to the closedposition. This enables the kinetic energy of the armature member,developed as the valve moves to the closed position, to be dissipated atleast in part without a direct effect on the valve member.

The continued movement of the armature member can be arrested by, forexample, having it strike an abutment whereupon further kinetic energyis dissipated by the impact and the rebounding of the armature member.During the rebound movement, which is in the first direction, furtherenergy is dissipated, and the armature member will again contact thevalve member. The continued movement of the armature member after thevalve has reached the closed position, and the impact of the armaturemember with the abutment both contribute to the energy dissipation ofkinetic energy without influencing the state of the valve member. Whenthe valve member is again contact by the armature member, after therebound movement, there will be little energy available to effect bounceof the valve member.

Conveniently, the electromagnetic means is a solenoid arranged co-axialwith the direction of movement of the valve member, which is preferablya poppet valve opening to downstream of the fuel flow.

Preferably the fuel injection apparatus includes a chamber in which ametered quantity of fuel is held, said port through which the fuel isdelivered being in the wall of said chamber, with the stem of the valvecontrolling the port extending across the chamber and through theopposite wall. A flexible diaphragm seal is provided between the valvestem and said opposite wall to permit the relative movement therebetweenas the valve opens and closes the port. The diaphragm is sealablysecured about the inner periphery to the stem of the valve and about theouter periphery to said opposite wall of the chamber.

Having regard to the flexibility of a diaphragm, there is a minimum ofresistance to the movement of the valve stem during the opening andclosing of the port. The low resistence nature of the seal between invalve stem and chamber wall contributes to accuracy in the timing of theopening and closing of the port, and the force required to effect themovement of the valve. Also the diaphragm seal is not subject to wear,as are other seals such as `O` ring seals and the like.

The use of an effective seal between the valve stem and chamber wallenables the solenoid that drives the valve to be effectively sealed fromthe chamber housing the metered quantity of fuel and from any air orother gas that effects delivery of the fuel from the chamber through theport. In one embodiment the solenoid is located in an area flooded withfuel but isolated form the chamber that receives the metered quantity offuel. This flooding of the solenoid area protects the metalliccomponents of the solenoid from exposure to water in liquid or vapourform that may promote corrosion of the metallic components. Alsodesirable damping effects on the free movement of the armature of thesolenoid result from the flooding of the solenoid area with fuel.

It is customary to arrange the chamber that holds the metered quantityof fuel co-axial with the valve and valve stem, and the fuel isdelivered from a metering device into a conduit extending laterally fromthe chamber.

When air or another gas is admitted to the chamber to displace a meteredquantity of fuel from the chamber for delivery to the engine, it isimportant that the quantity of fuel metered into the chamber is thequantity delivered to the engine. In particular, if there is not asignificant movement of air in the conduit between the fuel meteringdevice and the chamber, fuel can be left there. Any fuel remaining inthat conduit can reduce the actual quantity of fuel delivered to theengine relative to the metered quantity delivered into the conduit andhence detract from the engine's performance. This inaccuracy in thequantity of fuel delivered to the engine can be especially significantin small capacity engines, particularly at low fueling levels, such as alow load, low speed operation.

Accordingly, it is proposed to provide in a fuel injection system,having a chamber from which fuel is delivered to an engine, means tosupply air to the chamber to displace the fuel therefrom, a conduitcommunicating a fuel metering device with the chamber and through whichfuel delivered by the fuel metering device passes to the chamber, andmeans to admit air to said conduit adjacent the metering device toconvey the fuel in said conduit to the chamber.

The admission of the air to the conduit at or near where the fuel isdelivered thereinto, promotes an air flow through the conduit to thechamber, the air carrying with it fuel located in the conduit to bedelivered to the engine. If all of the air used to deliver the fuel isdelivered otherwise into the chamber, any fuel located in the conduit isnot entrained in the air, and so the total of the metered quantity offuel is not delivered to the engine. Conveniently all of the airrequired to deliver the fuel is admitted to the conduit adjacent themetering device.

The invention will be more conveniently understood from the followingdescription of one practical arrangement of the fuel injection andmetering device with reference to the accompanying drawing:

FIG. 1 is a longitudinal sectional view of the fuel injection andmetering device.

Referring to the drawing, the fuel injection and metering apparatuscomprises a body 10 having a projecting spigot 11 which in use isreceived in sealing relationship via the `O` ring 12 in a bore providedin the cylinder head or cylinder wall of an engine. When the spigot 11is so located the port 13 is in a position to deliver fuel into theengine combustion chamber when the valve 14 is in the open position ashereinafter described.

By suitable modification to the mounting arrangement this metering andinjection device may be fitted to deliver fuel in the induction systemof an internal combustion engine.

The valve stem 15, which carries the valve 14, extends co-axiallythrough the fuel chamber 16 in the spigot 11, and the central cavity 17in the solenoid assembly 18 mounted in the body 10. The diaphragm sealassembly 19 provides a seal between the valve stem 15 and the body 10 sothe fuel chamber 16 is isolated from the cavity 17 and the solenoidassembly 18 in general. The solenoid assembly 18 is slidably received inthe cavity 17 with the `O` ring seal 20 located therebetween. The axialposition of the solenoid assembly 18 in the cavity 17 is controlled bythe clamp bolts 21 and the Belleville (Trade Mark) washers 22 so theaxial position of the solenoid relative to the valve stem 15 can beadjusted as hereinafter described.

The valve 14 is held in the position to close the port 13 by thecompression spring 25 which is compressed between the spacer sleeve 26and the spring cap 27, which co-operates with the annular spring clip 28seated in a peripheral groove in the valve stem 15. The lower end of thespacer sleeve 26 rests on the clamp plate 29 which is received in arecess 38 in the body 10 in which the seal assembly 19 is also located.

The washers 22 sit on the upper face of the clamp plate 29 and when thewashers 22 are compressed by the tightening of the clamp bolts 21, theperiphery of the flexible diaphragm 45 is pressed against the body.

The armature 30 of the solenoid assembly 18 is of a generallycylindrical form and has freedom for axial movement in the bore 31 inthe cover plate 32. The armature 30 has an internal annular shoulder 33which abuts the pressure pad 34 seated on the upper end of the valvestem 15. The compression spring 35 is located between the pad 34 and theadjustor block 36 threadably received in the extension of the bore 31.The effective spring load holding the valve 14 closed is the differencebetween the upward force on the valve stem 15 derived from the spring 25and the downward force on the stem 15 derived from the spring 35. Thedegree of compression of the spring 25 is fixed by the non-adjustabledistance between the spring clip 28 and the upper end of the sleeve 26and the compression of the spring 35 is controlled by the position ofthe adjustor block 36. The adjustment of the compression of the spring35 is effected after the stroke of the armature 30 has been set ashereinafter described.

It will be noted that in the static condition as depicted in thedrawing, with the valve 14 closing the port 13, the armature 30 issupported on the pad 34 by the engagement of the pad with the shoulder33. In this static condition, the lower end of the armature 30 is spacedaxially from the solenoid core 40 as indicated by the gap 41, that gapbeing adjustable by means of the clamp bolts 21 and the Bellevillewashers 22. It will be appreciated that the gap 41 represents the extentof movement of the valve 14 is opening the port 13 after the solenoidassembly 18 is energised to create a magnetic force which draws thearmature 30 downwardly as viewed in FIG. 1 until it abuts the upper endof the core 40. The downward movement of the armature 30 is directlytransmitted through the pad 34 to the valve stem 15 to effect theopening movement of the valve 14.

Upon de-energising the solenoid assembly 18, the resultant upward forcedeveloped by springs 25 and 35 will move the valve stem 15 upwardly sothat the valve 14 again closes the port 13. During this closing movementof the valve 14 kinetic energy is developed by the valve, valve stem andarmature as they move upwardly under the influence of the springs. Uponthe valve 14 seating in the port 13 upward .[.movment.]. .Iadd.movement.Iaddend.of the valve and valve stem is stopped and the kinetic energyprocessed by them, being relatively small is substantially dissipated bythe impact of the valve with the port. The armature 30 however hassubstantially more kinetic energy due to the greater mass thereof andcontinues its upward movement until it contacts the under face 37 of theadjustor block 36, thereby dissipating part at least of the kineticenergy independently of the valve 14 and valve stem 15. Any subsequentrebound of the armature 30 downwardly from the adjustor block 36 will behalted by the shoulder 33 contacting the pad 34 on the end of the valvestem 15 thereby dissipating further the kinetic energy of the armature.[.3.]. .Iadd.30.Iaddend.. The contacting of the shoulder 33 with thepad 34 during the downward rebound movement of the armature 30 mayresult in a minor degree of movement of the valve 14 away from the port13. However this movement will be quite small in comparison with therebound movement that would have occurred in the even that the armature30 was rigid with the valve stem 15 and did not have the relativefreedom of movement above described. Under some operating conditionsthere may be a further rebound of the armature 30 off the pad 34 againin an upward direction before all the energy is dissipated. In the eventof a second rebound there will be negligible effect on the valve 14.

When the injection and metering device is in use the cavity 17 may beflooded with liquid fuel so that the movements of the armature 30 takeplace with the armature immersed in the liquid fuel, thus providing adamping effect on the movements and contributing to the dissipation ofthe kinetic energy of the armature upon closing of the valve 14, andhence a reduction in the extent of bouncing of the valve 14 on the port13. The flooding of the cavity 17 with the liquid fuel also results inthe absence of air containing moisture within the cavity and socontributes to the control of corrosion of various components of themechanism located within the cavity 17. The provision of fuel to floodthe cavity 17 is by the passages 38 and 39 in the body 10 thatcommunicate with the fuel circulating through the metering device 50.

Steps must be taken to ensure there is no leakage of fuel from thecavity 17 into the chamber 15, as the latter receives accurately meteredquantities of fuel from the fuel metering device 50 for delivery to theengine and any leakage of fuel into or from the chamber 16 would varythe amount of fuel from that so metered. To this end the diaphragm sealassembly 19 is provided incorporating the flexible diaphragm member 45having an outer peripheral area clamped between the clamp plate 29 andthe shoulder 46 in the base of the recess 38 in the body 10 and an innerperipheral area gripped by the clamp disc 47 having a central borethrough which the stem 15 extends and is sealably bonded.

The body 10 has mounted on the side thereof the fuel metering device 50which delivers individually metered quantities of fuel into the passage51 which is in direct constant communication with the chamber 16. Thefuel device 50 is of a known construction and incorporates a port 52 andassociated ball valve 53 which is normally held in a position to closethe port 52 by the rod 54 operated by a suitable actuating mechanism(not shown in detail). The fuel metering device may be of the form asdescribed in reference to FIG. 4 of the drawings of our U.S. Pat. No.4,693,224 and .[.pending.]. Austrailian patent .[.application.]. No.567037.

The passage 51 and chamber 16 are normally in communication with asupply of compressed air or other suitable gas maintained at asubstantial pressure. Gas is supplied from the pressurised sourcethrough the duct 57 and open port 58 in the wall of the passage 51 inclose proximity to the port 52 of the fuel metering device. When thevalve 14 is moved to open the port 13 an airflow will be created whichenters through the port 58 into the passage 51 and then travels into andthrough the chamber 16 and outwardly through the port 13 into the enginecombustion chamber or air induction system. The metered quantity of fuelwhich has previously been delivered from the metering device 50 throughthe port 52 will be entrained in this air flow and be carried with theair through the port 13 into the engine combustion chamber or airinduction system.

As this air enters the passage 51 in close proximity to the point ofentry of the fuel into that passage, the air flow established in thepassage 51 and chamber 16 upon opening of port 13 will pick up and carrywith it substantially all of the metered quantity of fuel delivered bythe metering device 50 so as to maintain sameness between the meteredquantity of fuel delivered from the metering device 50 and the quantityof fuel delivered to the engine through the port 13. Accordingly, fuelthat may otherwise cling to the wall of the passage 51 is entrained inthe air flow and effectively carried through the chamber 16 anddischarged through the port 13. If the air was admitted to the chamber16 at a location that did not establish an air flow along the passage51, fuel in the passage may not be carried into the chamber and bedelivered through the port 13.

The claims defining the invention are as follows: We claim:
 1. A fuelinjection apparatus for delivering a metered quantity of fuel to anengine, comprising:a port through which the metered quantity of fuel isdelivered; a valve member operable to open and close said port; biasingmeans for resiliently urging said valve member in a rearward directionto a position to close said port; selectively energizableelectromagnetic means for displacing said valve member in a forwarddirection, upon energization, from a port closed position to a port openposition to permit the delivery of the metered fuel through the port,wherein said electromagnetic means includes an armature in abuttingcontact with said valve member, such that upon energization of saidelectromagnetic means, said armature and valve member move together inthe forward direction to open said port, and upon deenergization, saidarmature has limited free movement in the forward and rearwarddirections independent from said valve member, when said valve member isin the port closed position.
 2. A fuel injection apparatus as claimed inclaim 1, including an abutment means independent of the valve member andlocated in the path of the armature when moving in said rearwarddirection to limit the extent of free movement of the armature in saidrearward direction when the valve member is in the port closed position.3. A fuel injection apparatus as claimed in claim 2, wherein the valvemember, armature and abutment means are co-axially aligned in saidforward and rearward directions, said armature having an abutmentsurface in an opposed relation to the abutment means whereby the extentof said free movement of the armature in each direction is determined bythe axial spacing of the abutment means from the abutment surface on thearmature when the valve member is in the closed position and thearmature is in abutting contact with the valve member.
 4. A fuelinjection apparatus as claimed in claim 2, including a chamber havingsaid port formed in one wall thereof, means to deliver a meteredquantity of fuel into said chamber for delivery to the engine, saidvalve member including a valve head adapted to sealably co-operate withsaid port to close the port, a valve stem rigidly secured to said valvehead and extending through said chamber and through a wall thereofopposite the port, seal means between the valve stem and the oppositewall to prevent the leakage of fuel therebetween, the biasing meansbeing operably connected to the valve stem to urge the valve stem insaid rearward direction to maintain the valve head in sealing relationwith the port.
 5. A fuel injection apparatus as claimed in claim 4,wherein said electromagnetic means is mounted externally of the chamberand located such that said forward and rearward directions of movementof the armature are co-axial with the valve stem.
 6. A fuel injectionapparatus as claimed in claim 5, wherein the armature is supported tohave free movement in the axial direction between that end of the valvestem external of the .[.cavity.]. .Iadd.chamber .Iaddend.and saidabutment means.
 7. A fuel injection apparatus as claimed in claim 4,wherein the seal means is an annular diaphragm having the outerperiphery thereof secured in fixed sealed relation to the wall of the.[.cavity.]. .Iadd.chamber .Iaddend.and the inner periphery thereofsecured in fixed sealed relation to the valve stem.
 8. A fuel injectionapparatus as claimed in claim 5 or 6, wherein the chamber is formed in abody with the port opening through the body at one end of the chamber,said valve stem extending from the opposite end of the chamber into acavity formed in said body, the electromagnetic means being housed insaid cavity.
 9. A fuel injection apparatus as claimed in claim 8,wherein the electromagnetic means is adjustably mounted in the cavityco-axial with the valve stem so that the relative axial dispositiontherebetween may be adjusted to control the extent of axial movement ofthe valve stem when the electromagnetic means is energised.
 10. A fuelinjection apparatus as claimed in claim 9, wherein resilient means areoperably interposed between the wall of the cavity and theelectromagnetic means to urge the latter axially in said rearwarddirection, and clamp means are provided to displace the electromagneticmeans in said forward direction to effect said adjustment of therelative axial disposition of the electromagnetic means relative to thevalve stem.
 11. A method of delivering a metered quantity of fuel to anengine comprising:ejecting the fuel through a port to the engine;resiliently urging a valve member to a position to close the port;selectively energizing an electromagnetic means to move an armaturemember in a forward direction to displace the valve member from the portclosed position to permit delivery of the metered quantity of fuelthrough the port; selectively de-energizing the electromagnetic meanssuch that the valve member moves to the port closed position anddisplaces the armature member in the rearward direction, opposite tosaid forward direction; and halting the movement of the valve member atthe port closed position and thereafter allowing the armature member tocontinue in said rearward direction until stopped by an abutment meansindependent of the valve member.